Following the Curie symmetry principle and Aizu rule, we discovered there is a centrosymmetric-to-noncentrosymmetric phase transition in Ca(NO3)2(15-crown-5) at Tc = 205 K. The transition was confirmed by differential scanning calorimetry and second harmonic generation measurements. The transition gives rise to excellent ferroelectricity, such as a giant dielectric anomaly, with faster polarization switching (5×10(-5) s) of up to 10(7) times without showing fatigue. The ferroelectric mechanism is attributable to the coordination environmental distortion of the central Ca atom. This finding can throw light on the further research in metal-organic ferroelectrics.
Keywords: coordination distortion; crown-ether complexes; dielectricity; ferroelectricity; structural phase transitions.
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